Bolt Spacing Research Articles

Variasi Spasi Baut terhadap Kuat Geser Sambungan Baut pada Pelat Baja

Errors in planning the spaces/distances between the bolts can weaken or create defects in the connection. Therefore, a research on the effect of bolt space on shear strength of bolt joints on steel plates is needed to find out the influence of the distance between bolts to the strength of double bolt joints on steel plate joints, whereas the long-term goal of this study is to determine the effect of the distance between bolts to the strength of the bolt connection in a plate connection system having more than two bolts. In the planning, the connection used bolt connecting devices that meet SNI 1729:2015 requirements. A tensile testing machine was used and the direct test method was conducted for shear strength of bolts in the plate joint system using two bolts. The bolt sample was installed in the plate connection system then the connection system was given a tensile load until it broke in the bolt sample. The peak load of the experimental results indicated the shear strength of the double bolt connection on the plate fluctuates. Average peak load for the sample of group I (20 mm bolt space), group II (40 mm bolt space), group III (60 mm bolt space), group IV (80 mm bolt space) and group V (100 mm bolt space) are 21.962 kN, 23.512 kN, 22.925 kN, 23.725 kN and 22.975 kN, respectively. The experimental results from each sample group showed the average peak load strength was greater than the theoretical shear strength value of 17.4974 kN.

Performance of a novel ductile connection in steel-framed structures under fire conditions

The component-based model of a novel connection, which is designed to accommodate the high ductility demand of long-span steel beams in fire conditions, has been incorporated into the finite element software Vulcan. A single beam with the novel connections connecting it to rigid supports at both ends is first used to verify that the component-based model has been correctly incorporated into Vulcan, by comparing its results with those from detailed finite element models using the general-purpose package Abaqus. The performance of the novel connection has been compared with that of conventional connection types, including ideally rigid and pinned connections, end-plate and web-cleat connections, using a sub-frame model. Results show that, compared with other connection types, the novel connection provides much higher axial and rotational ductilities, to accommodate the deformations generated by the connected beam as its temperature rises. To optimize the performance of the novel connection under the tensile axial forces generated by the eventual catenary action of heated, unprotected beams at high temperatures, parametric studies have been carried out on the influence of four key parameters, including the temperature of the connection, the inner radius of its semi-cylindrical section, the plate thickness and the bolt spacing. It is found that it is possible to optimize connection thickness, protection level, and inner radius of the semi-cylindrical section in order to delay the occurrence of bolt pull-out failure, and thus enhance a beam's ultimate failure temperature. Finally, the combined static-dynamic solver of Vulcan is used to simulate the progressive collapse of a three-storey, three-bay frame with these novel connections. This progressive collapse simulation emphasizes the importance of connections for the survival of the entire structure in a fire event.

Design and numerical analysis of a damage-controllable mechanical hinge beam-to-column connection

This paper presents an innovative earthquake resilient steel beam-to-column connection with a mechanical hinge and a pair of buckling-restrained steel plates for seismic damage control of steel structures. The mechanical hinge is used to carry shear force while the buckling-restrained steel plates bolted to the beam flanges are used to transfer bending moment. Energy dissipation of the connection is provided through inelastic axial deformation of the steel plates. Design method of the connection was proposed to ensure that inelastic deformation was concentrated in the steel plates while other structural members remain essential elastic. The effects of the steel plate size, restraining member size and bolt spacing were investigated by a parametric study to provide design recommendations for preventing buckling failure of the steel plate. Based on results of a case study, theoretical equations for predicting the connection behavior were verified.

Experimental Study on the Shear Behavior of GFRP-Concrete Composite Beam Connections.

Monotonic push-out tests were carried out on 11 specimens having high-strength bolt, T-type perforated plate, or slot-type perforated plate connections to investigate the influence of different connection types on the interface performance of glass fiber reinforced polymer (GFRP)–concrete composite beams. The effects of the number of rows and spacing of high-strength bolts on the failure mode, load–slip relationship, and shear capacity were analyzed. The effects of the number and spacing of holes in the perforated plates, and the inclusion of transverse rebar were analyzed. The results show that the failure mode of the bolt specimens is brittle failure and the perforated plate is ductile failure. The single bolt connection has the lowest ultimate bearing capacity, while the single T-shaped and slotted perforated plates are 170% and 270% times greater. The rows and spacing have no difference in bolts. The perforated plate gradually decreased with an increase in rows and gradually increased with an increase in spacing. The transverse rebar can increase the ultimate bearing capacity and ductility in the plastic stage for perforated plate. Accordingly, there are good choices for interface connectors for GFRP–concrete composite beams, while bolt connectors need to be carefully chosen.

Performance of Light-Frame Wooden Structures (LFWSs) Subjected to Combined Wind and Flood Hazards

Yazdani, N.; Beneberu, E.; Baniya, A., and Efaz, I.H., 2020. Performance of light-frame wooden structures (LFWSs) subjected to combined wind and flood hazards. Journal of Coastal Research, 36(4), 834–843. Coconut Creek (Florida), ISSN 0749-0208.Although simultaneous flood and wind events may cause catastrophic damage in areas outside the Special Flood Hazard Areas, no current building codes require light-frame wooden structures (LFWSs) to be elevated or designed for the combined loads. The current study numerically investigated the performance of typical elevated and a slab-on-grade (SOG) LFWS buildings located in 100- and 500-year floodplains, respectively, against global failure because of combined flood and wind forces. Factors such as the direction of lateral loads, effect of buoyancy, and flood level difference between the building interior and exterior were considered. Additionally, the adequacy of foundation anchor bolt spacing provisions from the 2018 International Building Code and Bureau of Recovery and Mitigation were investigated. From the overall performance of the SOG-type building, it was found that a nonengineered building complying only with the minimum requirements set by building codes is likely to fail locally at the wall-foundation connection before any global failure. In cases of elevated buildings, two-story buildings are safer against overturning, sliding, and uplifting failures compared with one-story structures.

Mechanical Properties of Single Shear Plane of Bolted Steel Connection

A 5-storey portable steel tower based on prefabricated frame concept has been built in Jamilus Research Centre, UTHM. It is now undergoing laboratory testing for static and dynamic performance. In this study, the mechanical properties of the connections were investigated via their connection condition between elements (beam and column) and connectors. The frame elements were designed based on S275 steel grade of 77 mm x 77 mm hollow section with 3 mm thickness, and 8 mm thickness of connectors’ plate. The connection was subjected to single shear plane action which fastened by bolts. Mild steel (grade 4.6) and high tension (grade 8.8) bolts with 10 mm diameter size were used. Shear, bearing and tensile strengths of the bolts and steel plates were determined via tension testing using 50 tonnes of Universal Testing Machine (UTM). From the results, all bolts and steel plates have satisfied the design strengths requirement of 640 N/mm2 (high tension bolt), 240 N/mm2 (mild steel bolt) and 275 N/mm2 as required by EN 1993-1-8. Meanwhile the ultimate shear force of bolts was found within ranges of 25% (high tension) and 12.5% (mild steel) from their respective ultimate tensile force. Bearing failure was occurred at bolt hole of 3 mm thickness of steel plate but only when it was fastened to high tension bolt. No bearing failure occurred when mild steel bolt was used. It has proven that all bolt spacing and edges distances were sufficient, without tearing failure observed in all testing. Finally, the permissible bearing resistance were checked based on the ratio of experiment against the EN 1993-1-8 relationships, when it has shown to satisfaction if the value is less than 1 as recommended by previous researcher.

Parametric Study on the Ground Control Effects of Rock Bolt Parameters under Dynamic and Static Coupling Loads

Dynamic and static coupling loads (DSLs) are one of the most common stress environments in underground engineering. As the depth of a roadway increases over the life of a mine, the static load of the ground stress field increase multiplies, and the cyclic operation at the working face releases a large amount of dynamic energy. Therefore, deep roadways easily induce dynamic disasters during production. In this paper, a deep roadway numerical model was built with FLAC3D to test the deep roadway under DSLs and was simulated with 16 different support designs. The ground stability in each support condition was examined and compared in terms of the ground deformation and scope of failure. The underlying support mechanism was further analyzed with numerical modeling in view of the deformation in the surrounding rock mass induced by variations in the support parameters. The results show that shortening the bolt spacing is an effective measure to control the deformation of surrounding rock whatever DSLs or static load. Under static load, the larger the anchoring length is, the more stable the surrounding rock is. Under DSLs, end grouting length (S = 600 mm) and full grouting length (S = 1800 mm) can effectively control the deformation of surrounding rocks and enhance the stability of surrounding rocks. The results contribute to the design of supports in the field of underground coal mines and provide a basis for determining the reasonable support scheme for roadways.

Ground support performance in deep underground mine with large anisotropic deformation using calibrated numerical simulation (case of mine-H)

High-stress and complex geological conditions impose great challenges to maintain excavation stability during deep underground mining. In this research, large anisotropic deformation and its management by support system at a deep underground mine in Western Australia were simulated through three-dimensional finite-difference model. The ubiquitous-joint model was used and calibrated in FLAC3D to reproduce the deformation and failure characteristics of the excavation based on the field monitoring results. After modeling verification, the roles of mining depth also the intercept angle between excavation axis and foliation orientation on the deformation and damage were studied. Based on the results, quantitative relationships between key factors and damage classifications were presented, which can be used as an engineering tool. Subsequently, the performance of support system installation sequences was simulated and compared at four different scenarios. The results show that, first surface support and then reinforcement installation can obtain a better controlling effect. Finally, the influence of bolt spacing and ring spacing were also discussed. The outcomes obtained in this research may play a meaningful reference for facing the challenges in thin-bedded or foliated ground conditions.

The Influence of Room and Pillar Method Geometry on the Deposit Utilization Rate and Rock Bolt Load

In this article, a model of ore deposit in form of a lense carried out in the MineScape program, is presented. The lense had a thickness of 30 m, length along the strike 200 m, and the depth buried was for 80 m to 110 m below the surface. In the first layer, counting from the lowest level, a room and pillar method with variable geometry was designed. The width and length dimensions for rooms and pillars were: 4 m, 5 m and 6 m, respectively. For the selected part of the deposit, three variants of the system with variable geometry of rooms and pillars were designed, for which the deposit utilization coefficient was determined. The next stage of the research was to determine the influence of the geometry of the pillars and rooms on the range of the rock destruction zone around room excavations. For this purpose, numerical calculations using the three-dimensional Examine 3D program, based on the boundary element method, were made. The results of numerical tests were used to calculate the load of the rock bolt support, which is currently used in the zinc and lead underground mine “Olkusz-Pomorzany” in Poland. Currently in the mine, the bolt spacing is 1 m × 1 m, and the technology for fixing the bolt rod is based on resin cartridges that completely fill the bolt hole. In order to spread the spacing of the rock bolt support and to apply segmental fixing of the bolt rod, in the laboratory tests, rock bolt supports with increased strength were tested. Based on the results obtained, it was found that the rock bolt can be installed segmentally, using a cement grout, and its spacing can be increased to 2 m.

Discrete element method and support vector machine applied to the analysis of steel mesh pinned by rockbolts

The current designs of steel mesh pinned by bolts on steep rock slopes do not adequately consider the deformation of the mesh. This paper discusses the development of discrete element models of wire mesh and a moving rock block to simulate field conditions where an unstable rock located between the bolts slides along a joint to load the mesh. A series of parametric analyses were performed using 900 simulations to analyze the influences of various factors on the mesh response. A high tensile-strength steel wire mesh with 3 mm diameter wires was selected for the analysis. The mesh wires are more likely to rupture if the rock volume is larger than 1.5 m3 and the sliding angle is over 40°. For the scenarios that were simulated, the steel mesh typically experienced a bulge of 0.4–0.8 m when loaded by rock volumes up to 3 m3. A larger mesh bulge occurs when the loose rock originates close to the upper bolt in the surrounding pattern of bolts. The mesh bulge increases dramatically as the bolt spacing increases. The simulation results were used to create mesh performance prediction models via a support vector machine (SVM) approach. The design tool considers a mesh bulge of 0.5 m and wire rupture as design criteria. The simulation results were used to train and test SVM models to predict the mesh response for a wide range of influence factors.

Experimental and analytical study of lightweight floor system built-up with cold-formed profile steel sheet and hot-rolled steel plate (CFPSS-HRSP)

The focus of the present research is to develop a reusable and recyclable lightweight floor system fabricated with cold-formed profiled steel sheet (CFPSS) and hot-rolled steel plate (HRSP) connected through bolts. This paper presents the results of eighteen medium-scale specimens fabricated with varying lengths, bolt spacings and thickness to evaluate the flexural and failure behavior under three-point bending. The proposed system was fabricated in two phases; phase I was based on single CFPSS, whereas phase II was based on double thickness by nesting two CFPSS on top of each other. The test results indicate that phase II specimens carried 50 to 80% more load than the phase I specimens. It can be noted that the decrease in experimental load ratio correlated well with the increase in length ratio for phase II specimens. However, a higher variation of up to 18% in moment capacity was observed in phase I specimens whereas the corresponding phase II specimens, showed a variation of up to 8%. Besides, it was also observed that the mode of failure for phase I and phase II specimens varied with specimen length, CFPSS thickness and spacing between the bolts in a lightweight panel system. An analytical approach was developed based on the modified form of Newmark's equation along with a theoretical approach (up to yield). The average analytical deflection closely matched with the moderate length while the shorter and longer length specimens slightly deviated from the experimental results in both the phases.

Study on cold-formed and hot rolled steel composite panel system

This study on lightweight built-up composite panel comprises of cold-formed profiled steel sheet (CFPSS) built-up with a hot-rolled steel plate (HRSP) connected by bolts. The space between the CFPSS and HRSP was filled with cement mortar as an infill material to study the effect of the composite system's strength and failure behaviour. The testing was carried with eighteen medium scale composite panels under three-point bending tests in two phases. Phase I specimens was fabricated from a single CFPSS and phase II specimens using double (nested) CFPSS, at the bottom. Other parameters include the length of the specimen (700 mm, 1200 mm and 1700 mm) and bolt spacing along the length (L/4, L/6 and L/8). The experimental data were analysed based on idealised load-deflection plots. The results indicate that the shorter and longer length mortar filled specimens experienced higher ultimate load and initial stiffness than the without mortar infill specimens in both the phases. However, infilled mortar specimens in moderate length did not show considerable improvement in ultimate load and initial stiffness values in both the phases. The phase II specimens experienced higher load and ductility in post-debonding failure regime compared to the phase I specimens. Most of the specimens exhibited tearing of CFPSS as a mode of failure at ultimate load. The modified Newmark's analytical expressions using equivalent area method for infilled mortar were derived up to the elastic limit to determine the deflection. The analytical results are in good agreement with the experimental results for both the phases.

Discrete element analysis of the influence of bolt pattern and spacing on the force‐displacement response of bolted steel mesh

SummarySteel wire mesh held by a pattern of bolts can be used to stabilize a rock slope. Knowledge of the force‐displacement response of steel mesh is essential in the design of this support system. Laboratory tests have been used to test mesh that is held to rigid steel frames. These testing conditions differ from how steel mesh is held in the field by bolts. The existing laboratory test data may underestimate the deformation and overestimate the load‐bearing capacity of the steel mesh. This paper focuses on the response of the high tensile strength steel mesh held by commonly used bolt patterns. Discrete element models were used to study the force‐displacement response of the steel mesh pinned by bolts. The influences of different bolt patterns and varying ratios of bolt spacing on the effectiveness of steel wire mesh were analyzed. Relationships between the resistance force of steel mesh and bolt density at various mesh deformations were developed. These relationships can help engineers choose the bolt spacing and provide an estimate of the resistance force that a steel mesh can mobilize at a desired deformation limit for a given bolt pattern.

Strainburst characteristics under bolt support conditions: an experimental study

Strainburst, defined as a burst that occurs on the periphery of tunnels, is always associated with intact and hard brittle rocks and high geo-stress. In practical engineering, the prevention of strainburst by bolting does not achieve the desired effects. Deep insight into the strainburst process and mechanisms under bolt support conditions is necessary to ensure safe underground construction. In this study, strainburst characteristics under bolt support conditions were investigated using a true-triaxial rockburst testing system, which was equipped with an acoustic emission monitoring system. High-speed cameras were also used to capture the ejection failure process. Two indicators, namely kinetic energy and maximum decibel, were used to comprehensively evaluate the rockburst intensity. In addition, characteristic stresses, failure mode and cracking mechanisms under different bolt spacing conditions were investigated. The test results demonstrated that rockburst is greatly affected by the bolt arrangement. Rockburst changes from the way occurring in the form of a local failure in weak area to the way striking the bolt position and even the overall free face with the decrease in bolt spacing. The use of the bolt increases the rockburst intensity, but the intensity decreases as the bolt spacing decreases. Characteristic stresses including crack initiation stress, crack damage stress and peak strength increase monotonously with the use of bolt and the decreasing bolt spacing. During the strainburst, tensile failure dominates the cracking process regardless of bolt spacing; however, with the use of bolt and decrease in bolt spacing, tensile splitting near the free face become less obvious and the proportion of shear failure gradually increased.

Weightage Effect during Back-Calculation of Rock-Mass Quality from the Installed Tunnel Support in Rock-Mass Rating and Tunneling Quality Index System

In extensively used empirical rock-mass classification systems, the rock-mass rating (RMR) and tunneling quality index (Q) system, rock-mass quality, and tunnel span are used for the selection of rock bolt length and spacing and shotcrete thickness. In both systems, the rock bolt spacing and shotcrete thickness selection are based on the same principle, which is used for the back-calculation of the rock-mass quality. For back-calculation, there is no criterion for the selection of rock-bolt-spacing-based rock-mass quality weightage and shotcrete thickness along with tunnel-span-based rock-mass quality weightage. To determine this weightage effect during the back-calculation, five weightage cases are selected, explained through example, and applied using published data. In the RMR system, the weightage effect is expressed in terms of the difference between the calculated and back-calculated rock-mass quality in the two versions of RMR. In the Q system, the weightage effect is presented in plots of stress reduction factor versus relative block size. The results show that the weightage effect during back-calculation not only depends on the difference in rock-bolt-spacing-based rock-mass quality and shotcrete along with tunnel-span-based rock-mass quality, but also on their corresponding values.

Effects of the Opening on the Behavior of Composite Steel Plate Shear Wall (CSPSW)

Due to architectural, mechanical and even structural considerations, in some cases there is need to create some openings in the composite steel shear walls. Presence of the openings can considerably affect the wall behavior. Therefore, in this study, the effects of the opening on the behavior of composite steel shear walls are investigated. For this purpose, first an experimental specimen without opening is developed and tested. The outcomes of the experimental study are verified by existing data Then three series of the CSPSW specimens (four specimens in each series) with opening are built and tested. Accuracy and precision of these experimental outcomes is verified by twelve numerical models which are developed using ABAQUS software. Therefore, general behavior of the CSPSWs with opening are investigated according to the attained outcomes from numerical and experimental tests. In addition, some methods are proposed to reduce the negative effects of the opening on the behavior of CSPSW. Then a parametric study is performed to evaluate effects of different parameters namely concrete cover thickness, steel plate thickness, thickness of the strengthening plate installed around the opening and bolt spacing on general behavior of the CSPSW. In addition to study the effects of opening in behavior of CSPSW, in this paper a thorough investigation about the influence of different parameters on drift of the system is performed .Finally, a formula is proposed based on the developed numerical models to compute lateral displacements of the composite shear walls with openings. This formula can be utilized for deriving an intensification factor which can be applied to calculate displacement of the composite shear wall with openings from the responses of a wall without openings.

DEVELOPING A METHODOLOGY FOR USING THE CONTINUOUS STRENGTH METHOD FOR BUILT-UP I-SECTION

Built-up steel sections are widely used in the construction industry due to their wide range of compression resistance. The main objective of the study is to introduce an efficient and economic design methodology for built-up I-sections by using the Continuous Strength Method (CSM) equations. These I-sections are made from two C-sections with bolts spaced at a specific interval. This methodology includes the calculation of individual capacity of C-sections using the CSM base curve and conversion that to bolted I-sections by using I-section properties. The predicted capacities show that the modified application of CSM equations can predict compressive resistance with high accuracy for built-up I-sections. Though the effect of bolt spacing is not considered in this study, the proposed methodology paves the path for deriving CSM equations for built-up sections.

Elastoplastic analysis of anchored tunnel under seepage

In order to study the stress and displacement distribution of surrounding rock of full-length bonded anchor support tunnel under seepage. The surrounding rock is regarded as a uniform and continuous porous medium. The supporting reaction force and seepage force of the surrounding rock are converted into the axisymmetric radial volume force of the circular tunnel and act on the stress field. Considering the reinforcement of the surrounding rock parameters by the bolt, the mechanical model is established. The elastoplastic analysis method is used to derive the analytical solution of the stress and displacement elasticity of the surrounding rock and plastic analytical solution based on Mohr-Coulomb yield criterion, which can be used to obtain the expression of the radius of the plastic zone of the tunnel and the displacement of the wall. Finally, the calculation results of this paper are compared with the numerical simulation analysis. The results show that the influence of the seepage on the plastic zone range and the wall displacement is more serious. The length and pretension of the bolt are inversely related to the plastic zone range and the displacement of the wall. The bolt row spacing is positively correlated with the plastic zone range and the displacement of the wall. Under the same conditions, considering the seepage requires the anchor to provide greater support. In order to avoid the instability of tunnel caused by seepage, the length of the bolt can be reasonably increased, the bolt spacing can be reduced, and the bolt pretension can be increased.

Strength design of concrete-infilled double steel corrugated-plate walls under uniform compressions

Concrete-infilled double steel corrugated-plate walls (CDSCWs) are composed of two steel corrugated-plates (SCPs) which are connected through bolts, and concrete filled the spacing formed between the two SCPs. Two vertical boundary elements are installed additionally at both sides of CDSCWs. On the one hand, the corrugated configuration of SCPs has great improvement on the load-bearing efficiency of CDSCWs; on the other hand, much higher bearing capacities and better seismic performance for CDSCWs are provided owing to the interactions among SCPs, bolts and infilled-concrete. This paper investigates the load-bearing mechanism and strength design formulae of CDSCWs under compressions. Since SCPs are prone to local buckling failure between two rows of bolts under the conditions of large vertical bolt spacing and small thickness of SCPs, this paper mainly focuses on the load-bearing mechanism of SCPs in CDSCWs under uniform compressions. The unilateral constraint on SCPs provided from infilled-concrete and the restraining effect on the flexural deformation of SCPs owing to bolts are considered. At first, series of finite element (FE) eigenvalue buckling analyses are conducted to study the elastic buckling behavior of SCPs subjected to uniform compressions. On the basis of Euler's formula, the formulae for predicting the elastic buckling stresses and corresponding normalized slenderness ratios λs of SCPs are achieved respectively. The instability performance of SCPs under uniform compressions is then investigated through FE nonlinear analyses, and accordingly the stability coefficient φs is attained. The corresponding φs−λs curve is therefore established in order to calculate the ultimate bearing capacities of SCPs. In addition, the cooperative performance of material strengths between SCPs and concrete is analyzed numerically when CDSCWs reach their compressive ultimate strength. With this consideration, the design method for predicting the cross-sectional strength of CDSCWs under compressions is proposed. Moreover, a CDSCW specimen with I-section is tested under a compressive load. Its cross-sectional strength is investigated experimentally. The results of the experiment coincide with those of numerical simulation, this verifying the safety and validity of the design method for cross-sectional strength design of CDSCWs.

Lateral resistance of strapped wood shear walls

ABSTRACTThis paper summarizes the results of 15 tests from a study on the effects of different types of straps on the lateral resistance of wood shear walls without openings. The stud walls were built with oriented strand board (OSB) panels. Five types of straps were used to bind the stud walls to the base plates. In addition, the test variables were double sole base plates, anchor bolt spacing and different types of washers. The walls were 2.4 m (8 ft) in height and 3.6 m (12 ft) long with 40.5 cm (16 in.) stud spacing, used 8d ring shank nails and 100 mm/150 mm (4 in./6 in.) nail patterns for edge/field, which generally follows the Moore, Oklahoma’s Adopted New Building Code (2014). The results from the strapped walls were compared to the walls without straps. The test results illustrate the walls with Simpson LSTA9 showed the highest capacity compared to the walls with other types of straps. Overall, results indicate that the straps improve the wall capacity; moreover, the wall capacity improves significantly with the double base place and increases washer size in conjunction with the strapped wood.